Thermosetting Materials and Processes:

Thermosetting materials, also known as thermosets, are a type of polymer that undergoes a chemical reaction when heated and then cooled, resulting in a permanent change in their structure. This change makes them resistant to melting or softening when exposed to heat again. Thermosetting materials are widely used in various industries due to their superior mechanical, thermal, and electrical properties.

Processes for Thermosetting Materials:

1. Compression Moulding:
Compression moulding is a commonly used process for thermosetting materials. In this process, the thermosetting material is placed in a mould cavity, and then heat and pressure are applied to shape and cure the material. The high pressure ensures that the material completely fills the mould cavity and the heat activates the curing reaction, transforming the material from a soft, moldable state to a hardened, rigid state.

2. Transfer Moulding:
Transfer moulding is another process used for thermosetting materials. It is similar to compression moulding, but with an additional step. In this process, the uncured thermosetting material is first preheated in a separate chamber called a "pot". Then, it is forced into the mould cavity under pressure. The heat and pressure applied during transfer moulding facilitate the curing process and shape the material into the desired form.

3. Injection Moulding:
Injection moulding is not commonly used for thermosetting materials. This process involves melting the material and injecting it into a mould cavity under high pressure. However, since thermosetting materials cannot be melted or softened again after curing, injection moulding is not suitable for these materials as it requires a reversible melting process.

4. Extrusion:
Extrusion is also not commonly used for thermosetting materials. This process involves forcing the material through a die to produce continuous shapes such as pipes, tubes, or sheeting. However, since thermosetting materials cannot be melted or softened again after curing, the extrusion process is not suitable for these materials.

Conclusion:

Based on the above explanation, the correct answer is option 'B' - Compression moulding and Transfer moulding are the processes commonly used for thermosetting materials. Injection moulding and extrusion are not suitable for thermosetting materials due to their irreversible curing process.